BackgroundAs research has shown that positive energy balance is a predominant factor underlying the development of obesity, it is important to seek strategies that can be used to augment the effects of exercise in the prevention and treatment of the condition. Recent studies have shown that dairy may have a protective effect against the development of obesity in both humans and rats. However, few studies have examined the individual and combined effects of dairy intake and endurance exercise.PurposeThe purpose of this study was to compare individual and combined effects of dairy and endurance exercise training on gut microbiota abundance and serum metabolites in relation to metabolic parameters including weight gain, adiposity, and circulating mediators (e.g. glucose, insulin, free fatty acids).MethodsAn 8‐week feeding intervention of a high‐fat, high‐sugar diet was used to induce obesity in male Sprague‐Dawley rats. Rats were assigned to one of four groups for 6 wk: i) high fat (n=12), ii) dairy (n=14), iii) dairy+exercise (n=9), and iv) exercise alone (n=9). Rats underwent acclimation sessions prior to commencing training. Incremental exercise training took place 5 d/wk on a motorized treadmill. Fresh fecal samples were collected prior to sacrifice. Total DNA was extracted and quantified, and microbial profiling was conducted using qPCR. Data are reported as relative abundance. Serum metabolmics from fasting samples were assessed by 1H‐NMR, ICP‐MS and GC‐MS.ResultsDairy+exercise treatment attenuated weight gain more than either dairy or exercise alone (p<0.05). Microbial profiling of fecal matter revealed that dairy but not exercise increased the relative abundance of Bifidobacterium spp.(p<0.05). Exercise alone increased the relative abundance of Methanobrevibacter spp., Akkermansia muciniphila, Collinsella Aerfaciens, and Bacteroides/Prevotella spp., while the combination of dairy+exercise negated these impacts (p<0.05). In addition, dairy, exercise, and the combination of dairy+exercise reduced the abundance of Clostridium Cluster XI, a bacterial group previously shown to be elevated with high fat feeding. Serum metabolomics profiling demonstrated the most robust separation with dairy treatments (p<0.05). Metabolites driving the separation included those most closely associated with one carbon metabolism, TCA cycle intermediates, and those associated with dairy consumption (e.g. calcium, potassium).ConclusionDairy and exercise treatments appeared to have distinct impacts on both microbial and serum metabolomics profiles. Importantly, the impacts of dairy were profound and larger than anticipated, especially on microbial profiles. This work demonstrates that the impacts of dairy and exercise were distinct but additive on these parameters, likely working synergistically to maintain body weight.Support or Funding InformationDairy Farmers of Canada (DW), NSERC (JS, RAR, DW).This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.